SpamTitan Sender List Management

Overview

SpamTitan maintains two key sender policy lists that override the spam filtering engine: the allowlist (trusted senders whose mail is always delivered) and the blocklist (blocked senders whose mail is always rejected or quarantined). Proper list management is essential for MSPs to balance effective spam filtering against business continuity — preventing false positives from disrupting client workflows while blocking persistent unwanted senders.

Anti-triggers

• Deciding what to do with a message already sitting in quarantine —

use SpamTitan Quarantine.

• Blocking a sender in another vendor's engine — sender lists do not

federate. Ironscales keeps its own allowlist behind IRONSCALES Incidents, and every other gateway keeps its own too; allowlisting here changes nothing anywhere else.

• Mail-flow rules inside the tenant — these lists live in the

SpamTitan gateway, upstream of Exchange Online. Forwarding, inbox rules, and mailbox-level mail flow are Microsoft 365 Mailboxes or cipp-mailboxes.

Key Concepts

Allowlist (Trusted Senders)

The allowlist contains senders whose email is delivered directly to users' inboxes, bypassing spam scoring. Use the allowlist for:

• Legitimate business partners whose emails are frequently misclassified as spam
• Bulk notification systems (monitoring alerts, business SaaS tools) that trigger spam rules
• Internal relay servers or third-party mailing services used by the client
• Vendors with IP-based reputation issues beyond their control

Caution: Allowlisting bypasses spam filtering entirely. Only allowlist senders you have explicitly verified as legitimate. Attackers frequently spoof trusted sender addresses.

Blocklist (Blocked Senders)

The blocklist causes matching emails to be immediately rejected or quarantined, regardless of their spam score. Use the blocklist for:

• Known spam campaigns with persistent sending addresses
• Domains that have been identified as malicious or compromised
• Senders that bypass spam scoring with low-score messages but are clearly unwanted
• Former vendors or partners whose mail is no longer wanted

Entry Types

The sender parameter on both tools accepts:

• Email address — e.g., [email protected] — matches only that exact address
• Domain — e.g., @example.com — matches all senders from that domain

Add IP entries in the SpamTitan admin interface.

Per-Domain vs. Global Lists

The SpamTitan appliance itself distinguishes global entries from per-domain ones, and per-domain entries are what you want in an MSP environment — a global entry affects every client the gateway filters for.

There is no domain or scope parameter, so an entry added through these tools lands at whatever default scope the appliance and API key give it. If a client-scoped entry is required, add it in the SpamTitan admin interface and record the reason there; do not claim a per-domain scope you did not set.

API Patterns

List Allowlist Entries

Listing is an argument, not a separate tool: call spamtitan_manage_allowlist with action: "list".

{
  "action": "list"
}

Parameters (complete — there is no domain, type, page, or limit):

• action — Required. add, remove, or list
• sender — Email address or domain. Required by the handler for add and

remove; ignored for list

• note — Free-text reason recorded with the entry (for add)

Omitting action makes the server elicit it from the caller. An unattended agent cannot answer an elicitation, so the call stalls instead of proceeding.

The list is returned whole — there is no pagination on this call, so a large list arrives in one response.

Example response:

The server wraps whatever the appliance returns as { "allowlist": [...] }. Entry shape is the appliance's, not this connector's — expect something like:

{
  "allowlist": [
    {
      "id": "al-00491",
      "entry": "[email protected]",
      "type": "email",
      "domain": "clientcorp.com",
      "added_at": "2026-01-15T10:30:00Z",
      "added_by": "[email protected]",
      "notes": "PagerDuty monitoring alerts — falsely quarantined"
    }
  ]
}

Note the response may carry a domain on an entry even though you cannot set one through this connector — that reflects how the entry was created, which may have been in the admin interface.

Add or Remove Allowlist Entries

Same tool, different action.

spamtitan_manage_allowlist

Parameters:

• action — Required. add, remove, or list
• sender — The sender address or domain (e.g. [email protected] or

@example.com). Required for add and remove

• note — Reason for adding (strongly recommended for audit trail; applies to

add). Singular note, not notes

Example — Add email address to allowlist:

{
  "action": "add",
  "sender": "[email protected]",
  "note": "CRM notification emails — quarantined due to bulk mail score"
}

Example response:

{
  "success": true,
  "message": "'[email protected]' added to allowlist"
}

Example — Remove an entry from allowlist:

{
  "action": "remove",
  "sender": "[email protected]"
}

List Blocklist Entries

Same shape as the allowlist: spamtitan_manage_blocklist with action: "list".

{
  "action": "list"
}

Parameters (complete — there is no domain, type, page, or limit):

• action — Required. add, remove, or list
• sender — Required for add and remove
• note — Free-text reason (for add)

Example response (wrapped as { "blocklist": [...] }):

{
  "blocklist": [
    {
      "id": "bl-00201",
      "entry": "@persistent-spammer.net",
      "type": "domain",
      "scope": "global",
      "added_at": "2026-02-28T09:00:00Z",
      "notes": "Confirmed spam campaign — multiple clients targeted"
    }
  ]
}

Add or Remove Blocklist Entries

spamtitan_manage_blocklist

⚠ HIGH-IMPACT — the server marks this tool `destructiveHint: true` and opens its own description with a warning. One add can silently stop a customer's legitimate mail: there is no bounce visible to the recipient and no alert, so the sender simply stops arriving, sometimes for weeks before anyone notices. A domain-scoped entry against a shared sending service takes out every customer using it. And because this connector has no domain parameter, you cannot confine the entry to one client from here. Confirm with a human before every add and every remove; action: "list" is the only benign call on this tool.

Parameters:

• action — Required. add, remove, or list
• sender — The sender address or domain to block (e.g. [email protected] or

@evil.com). Required for add and remove

• note — Reason for blocking (required as audit-trail practice, optional to

the API). Singular note, not notes

Example — Block a domain:

{
  "action": "add",
  "sender": "@confirmed-malicious.ru",
  "note": "Confirmed phishing domain — identified in multiple client incidents 2026-03-02"
}

Example response:

{
  "success": true,
  "message": "'@confirmed-malicious.ru' added to blocklist"
}

Example — Remove a blocklist entry (e.g., false positive block):

{
  "action": "remove",
  "sender": "[email protected]"
}

Common Workflows

Resolving a Quarantine False Positive with Allowlisting

1. Identify the falsely quarantined sender via the quarantine queue
2. Confirm the sender is legitimate by reviewing headers, links, and content
3. Call spamtitan_manage_allowlist with action=list to check if the sender is already listed (may need to be updated)
4. Call spamtitan_manage_allowlist with action=add and the sender address or domain
5. Release the quarantined message with spamtitan_release_message — a separate call; release does not allowlist
6. Document the allowlist entry with a clear note value explaining why the sender is trusted

Blocking a Persistent Spam Campaign

1. Identify the spam sender from the quarantine queue or a user complaint
2. Check if other clients are receiving the same mail (cross-domain pattern)
3. Recognise that you cannot choose the scope from here — these tools take no domain parameter, so the entry lands wherever the appliance and API key put it. If the block must be confined to one client, do it in the SpamTitan admin interface instead
4. Call spamtitan_manage_blocklist with action=add, the sender, and a descriptive note. Get a human to confirm first — this is the high-impact tool
5. If blocking a domain rather than a single address, confirm the domain is not a legitimate shared sending service (e.g., never block @gmail.com)
6. Delete any existing quarantined messages from the same sender with spamtitan_delete_message, one message_id per call

Reviewing and Auditing List Entries

1. Call spamtitan_manage_allowlist and spamtitan_manage_blocklist, each with action=list. Both return the appliance-wide list — there is no per-client filter, so attribute entries to clients yourself from the sender values
2. Review entries older than 6 months — vendors and partners may have changed, and allowlist entries should be periodically revalidated
3. Look for overly broad domain allowlists that may create a security risk (e.g., allowlisting an entire popular domain)
4. Remove stale entries with spamtitan_manage_allowlist or spamtitan_manage_blocklist using action=remove
5. Document the review in the client's PSA ticket for compliance records

Blocking After a Phishing Campaign

1. After identifying and deleting a phishing campaign in the quarantine queue, note the sending domain
2. Add the sending domain with spamtitan_manage_blocklist, action=add. It applies at the appliance's default scope, not a client's — confirm that is acceptable before you call
3. IP-based entries are not expressible through this connector's sender parameter; block a sending IP in the SpamTitan admin interface
4. Check whether any related domains (typosquats or same registrant) should also be blocked
5. Verify the block is effective by checking subsequent quarantine entries — the sender should no longer appear

Error Handling

Duplicate Entry

Cause: Attempting to add an entry that already exists in the list Solution: Call the same tool with action=list to check existing entries before adding

Missing action

Cause: action is the only required parameter, and it was omitted Solution: The server elicits it interactively. An unattended agent cannot answer, so pass action explicitly on every call

Missing sender

Cause: action=add or action=remove without a sender Solution: The handler returns 'sender' is required when action is 'add' (or 'remove'). Supply it; sender is ignored only for action=list

Entry Not Found on Remove

Cause: Attempting to remove an entry that doesn't exist or uses a different format than what was added Solution: Call action=list and use the exact sender value that appears in the response

Invalid Entry Format

Cause: Submitting an improperly formatted email address or domain Solution: Ensure domains use the @domain.com format and email addresses include both local part and domain. IP entries are not addressable through the sender parameter — use the SpamTitan admin interface

Permission Denied

Cause: API key does not have permission to manage lists Solution: Verify API key scope with your SpamTitan admin. There is no per-call domain scope to adjust — these tools take no domain parameter

Best Practices

• Always provide a note when adding list entries — six months from now, no one will remember why a sender was allowlisted
• Prefer allowlisting specific email addresses over entire domains when possible; domain allowlisting is a broader trust grant
• Never allowlist based on a user's request alone — always verify the sender is legitimate before adding
• Review allowlists and blocklists quarterly with action=list; stale entries accumulate and become a security and maintenance burden
• Document the threat intelligence source in the note on every blocklist entry (e.g., "Confirmed phishing — seen across 3 client accounts on 2026-03-02"). Since scope cannot be confined from here, treat every entry as potentially appliance-wide and write the note accordingly
• Be cautious about blocking shared sending services (SendGrid, Mailchimp, etc.) — block the specific sending address or subdomain, not the entire service
• Cross-reference blocklist additions with allowlists — a sender cannot be in both lists simultaneously

Related Skills

• api-patterns - Authentication, pagination, and error handling
• quarantine - Quarantine queue management where list decisions originate